In general, humidifiers vaporize water and expel the vapor into the surrounding environment in order to increase the moisture content thereof. Such increased humidity may be desirable in order to improve the comfort level for individuals experiencing the humidified air. For example, during cold weather indoor humidity levels can drop causing drying of skin or throat and adding to the discomfort of respiratory infections. While humidifiers may be used in a variety of circumstances, they are especially useful in maintaining a comfortable humidity level in otherwise low humidity conditions. Humidifiers are available in a variety of sizes and designs and include both console units and portable units. Console units typically are large stationary units having the humidifying capacity to affect large areas such as an entire house. Portable units are smaller in size and usually have the humidifying capacity to meet the requirements of a single room. Portable humidifiers due to their small size permit them to be moved from room to room as required. In addition, portable humidifiers utilize various means of producing the water vapor including heating coils, ultrasonic transducers and evaporative wicks.
Conventional construction of a portable humidifier includes a base unit containing a water reservoir in which the water is held just prior to vaporization by a humidification device. Water is supplied to the reservoir by a supply tank which is removably supported in the base. The tank may be removed as required in order to replenish the water supply. Water is typically introduced into the tank through a fill hole which is covered by a removable cap.
Water is typically transferred from the tank to the base reservoir through a valve assembly disposed in the bottom of the tank. When the tank is placed in the base, the valve engages a member on the base which urges the valve into an open position thereby allowing the water to flow into the reservoir. As water flows from the tank to the reservoir, air simultaneously is drawn into the tank through the valve by the vacuum created from the exiting water. When the water level in the reservoir rises to such a degree that the valve opening becomes covered with water, a hydrostatic balance is reached and the flow of water ceases. As water is vaporized, the reservoir level drops disturbing the balance and resulting in the continued flow of water from the tank. This controlled flow cycle ensures that the humidification device will have a supply of water with which to vaporize, as well as limiting the amount of water such that no water spills over the edges of the base reservoir.
The water which is stored in the supply tank is typically obtained from the tap. Such water may be supplied through a municipal water system or through a well located on site. Untreated tap water typically contains various impurities dissolved in and/or carried by flowing water. Common contaminants include salts of calcium and magnesium, metals such as copper and lead which has leached out from the plumbing and sediment type particulate. Water supplies may also be contaminated with volatile organic compounds and trihalomethane. In addition, municipal water supplies are often treated with a chlorine based compound for disinfection purposes in order to neutralize bacteria or other potentially harmful organisms found in the water supply. All of the aforementioned contaminants can hinder the effectiveness of the humidifier and offset the benefits thereof.
The water borne contaminants detrimentally effect each of the various types of humidifiers which are commercially available. Wick type humidifiers rely on a cellulose composed wick to absorb water through a capillary action. The water is then evaporated from the wick by a forced stream of air directed over the wick. Upon evaporation of the water most of the contaminants precipitate out and remain on the wick. However, after a period of time the precipitates, such as the dissolved minerals and sediment, tend to form at the base of the wick and the wick basin. These precipitates tend to clog the wick thereby reducing its ability to absorb water.
Heat type humidifiers transform water to a vaporized state through the application of heat by way of an electrical resistance coil or disc. The heating chamber from which the water evaporates eventually becomes coated by a with a build up of residue from the minerals, known as scale, and other contaminants contained in the water. This residue may result in an obstruction to the flow of water into the heating chamber and otherwise decrease the efficiency of the humidifier. Therefore, the humidifier must be cleaned frequently to remove the unwanted deposits.
Nebulizing humidifiers which atomize the water typically by way of an ultrasonic transducer expel the water including its contaminants into the air. The contaminants carried by the aerosolized water droplets eventually precipitate out creating a residue which is commonly known as white dust. This dust forms on and around the humidifier resulting in the need for frequent cleaning. Attempts have been made to control this problem by employing a filter between the water supply and the humidification device. Such filters are of the deionization type which remove the ions of the dissolved minerals in the water such as calcium or magnesium. These filters, while eliminating the contaminants which form white dust, they still permit various substances such as chlorine to pass through and enter the air.
Some of the contaminants which are permitted to be vaporized may have harmful side effects on exposed individuals. Wick and heat type humidifiers allow tap water contaminants which are volatile, such as chlorine and organic compounds, to evaporate into the air and become an inhalant. Nebulizing humidifiers atomize chlorine containing water such that it may be inhaled. Several authorities have suggested that evaporated chlorine compounds which are transformed into an inhalant, i.e., either as a gas or nebulized water particles, may cause potentially harmful health effects to exposed individuals.
In addition to the use of wicks and deionizing type filters to remove contaminants from tap water, various attempts have been made to filter humidifier supply water to reduce the amount of contaminants entering the air. One such device is disclosed in U.S. Pat. No. 4,604,264 to Choe. Choe discloses a combination humidifier and water distiller apparatus. The device includes a container for holding tap water and a heater for heating the tap water in the container to a vaporized state. A condenser is positioned above the container and condenses the vaporized water such that the water, now distilled, drops down and is collected. The distilled water is then transported via a water track and valve to a humidification chamber where the water is nebulized and delivered as a fine spray to the atmosphere thereby humidifying the surrounding air. However, the humidifier of Choe while purifying the water does not prevent substances such as chlorine from entering the environment when the water is vaporized. Also, the minerals that precipitate out during the distilling process must be cleaned from the heater. In addition, a device which requires both a distilling heating element and a humidification device would prohibitively expensive to manufacture and successfully market.
Filters which purify tap water by removing minerals and other contaminants such as chlorine are known in the art. However, due to their size they have been difficult to incorporate in the relatively tight size constraints found in a portable humidifier. The size of the filter must be large enough so that its effective filtration life is long enough to make the product commercially viable. Heretofore, the prior art has been unable to produce the humidifier which can accommodate a purification filter which is commercially available.
Accordingly, it would be desirable to provide a humidifier which includes a filtration device capable of removing substantially all contaminants including minerals and chlorine from the water prior to its vaporization. It would also be desirable to provide a humidifier which is economically feasible to produce and is designed to accommodate a commercially available water filtration device.